package com.jiangyg.mall.core.utils;

import lombok.extern.slf4j.Slf4j;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import java.security.Key;
import java.util.Random;

/**
 * 密码加密
 * 支持算法：PBEWITHMD5ANDDES、PBEWITHMD5ANDTRIPLEDES、
 * PBEWITHSHAANDDESEDE、PBEWITHSHA1ANDRC2_40、PBKDF2WITHHMACSHA1
 *
 * @author jiangyg
 */
@Slf4j
public class PasswordUtils {

    /**
     * 定义使用的算法为:PBEWITHMD5andDES算法
     */
    public static final String ALGORITHM = "PBEWITHMD5ANDDES";

    /**
     * 定义迭代次数为1000次
     */
    private static final int ITERATIONCOUNT = 1000;

    /**
     * 加密明文字符串
     *
     * @param plaintext 待加密的明文字符串
     * @param password  生成密钥时所使用的密码
     * @param salt      盐值
     * @return 加密后的密文字符串
     */
    public static String encrypt(String plaintext, String password, byte[] salt) {
        Key key = getPBEKey(password);
        byte[] encipheredData = null;
        PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, ITERATIONCOUNT);
        try {
            Cipher cipher = Cipher.getInstance(ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, key, parameterSpec);
            encipheredData = cipher.doFinal(plaintext.getBytes());
        } catch (Exception e) {
            Logger.error(log, () -> "加密明文字符串出错：", e);
        }
        return bytesToHexString(encipheredData);
    }

    /**
     * 解密密文字符串
     *
     * @param ciphertext 待解密的密文字符串
     * @param password   生成密钥时所使用的密码(如需解密,该参数需要与加密时使用的一致)
     * @param salt       盐值(如需解密,该参数需要与加密时使用的一致)
     * @return 解密后的明文字符串
     * @throws Exception 解密异常
     */
    public static String decrypt(String ciphertext, String password, byte[] salt) throws Exception {
        Key key = getPBEKey(password);
        PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, ITERATIONCOUNT);
        try {
            Cipher cipher = Cipher.getInstance(ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, key, parameterSpec);
            byte[] passDec = cipher.doFinal(hexStringToBytes(ciphertext));
            return new String(passDec);
        } catch (Exception e) {
            Logger.error(log, () -> "解密密文字符串出错：", e);
            throw e;
        }
    }

    /**
     * 生成密码私盐随机数
     *
     * @return String
     */
    public static String getSaltRands() {
        Random rd = new Random();                             // 创建随机对象
        StringBuilder n = new StringBuilder();                 // 保存随机数
        int rdGet;                                             // 取得随机数
        do {
            if (rd.nextInt() % 2 == 1) {
                rdGet = Math.abs(rd.nextInt()) % 10 + 48;     // 产生48到57的随机数(0-9的键位值)
            } else {
                rdGet = Math.abs(rd.nextInt()) % 26 + 97;     // 产生97到122的随机数(a-z的键位值)
            }
            char num1 = (char) rdGet;                         // int转换char
            String dd = Character.toString(num1);
            n.append(dd);
        } while (n.length() < 8);                             // 设定长度，此处假定长度小于8
        return n.toString();
    }

    /**
     * 将字节数组转换为十六进制字符串
     *
     * @param src 字节数组
     * @return String
     */
    public static String bytesToHexString(byte[] src) {
        StringBuilder stringBuilder = new StringBuilder();
        if (src == null || src.length == 0) {
            return null;
        }
        for (byte b : src) {
            int v = b & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2) {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }

    /**
     * 将十六进制字符串转换为字节数组
     *
     * @param hexString 十六进制字符串
     * @return byte[]
     */
    public static byte[] hexStringToBytes(String hexString) {
        if (hexString == null || hexString.equals("")) {
            return null;
        }
        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
            int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
        }
        return d;
    }

    /**
     * 根据PBE密码生成一把密钥
     *
     * @param password 生成密钥时所使用的密码
     * @return Key PBE算法密钥
     */
    private static Key getPBEKey(String password) {
        SecretKeyFactory keyFactory;                                        // 实例化使用的算法
        SecretKey secretKey = null;
        try {
            keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
            PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());    // 设置PBE密钥参数
            secretKey = keyFactory.generateSecret(keySpec);                    // 生成密钥
        } catch (Exception e) {
            Logger.error(log, () -> "根据PBE密码生成一把密钥出错：", e);
        }
        return secretKey;
    }

    private static byte charToByte(char c) {
        return (byte) "0123456789ABCDEF".indexOf(c);
    }

}
